Some hydraulic controls for power shift transmissions automatically provide for the sequential engagement of specific clutches after the transmission is shifted from one speed to another. For example, the system disclosed in U.S. Pat. No. 3,091,976 which issued to Johnson et al. on June 4, 1963 causes the speed clutches to be fully engaged before either one of the directional clutches is engaged so that the directional clutches absorb the shock of transmitting power through the transmission. With that system both the selector valve and directional control valve are directly controlled by the operator through a mechanical linkage. However, the control system of many of the industrial vehicles are being designed to incorporate pilot control circuits to control the shifting of the main control valves. Those pilot control circuits can be either totally hydraulic or a combination of electrical and hydraulic components. In either case, while the sequential engagement system taught by the above-noted patent has functioned satisfactory in the direct operator controlled arrangement in which it is used, that specific system is not readily convertible to a pilot operated control circuit.
The present invention is directed to overcoming one or more of the problems as set forth above.